Coordinate measurement machine with configurable articulated arm bus

ABSTRACT

An articulated arm coordinate measurement machine is provided with a configurable arm bus. The arm bus being comprised of a plurality of busses that may be selectively coupled to form one or more logical data communications busses. The logical busses may be configured to allow accessory devices to be coupled to the arm and transmit data at higher speeds and at lower costs than may be possible using data busses having fixed communications protocols. In one embodiment, one or more communications switches may be arranged in the probe end of the arm to selectively combine the busses into a logical bus.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation Application of U.S.application Ser. No. 14/868,974, filed on Sep. 29, 2015, which is aNonprovisional Application of U.S. Provisional Application Ser. No.62/060,866, filed on Oct. 7, 2014, the contents of which areincorporated by reference herein in their entirety.

BACKGROUND

The present disclosure relates to a coordinate measuring machine andmore particularly to a portable articulated arm coordinate measuringmachine having a bus that is selectively configurable to operate withmultiple data protocols.

Portable articulated arm coordinate measuring machines (AACMMs) havefound widespread use in the manufacturing or production of parts wherethere is a need to rapidly and accurately verify the dimensions of thepart during various stages of the manufacturing or production (e.g.,machining) of the part. Portable AACMMs represent a vast improvementover known stationary or fixed, cost-intensive and relatively difficultto use measurement installations, particularly in the amount of time ittakes to perform dimensional measurements of relatively complex parts.Typically, a user of a portable AACMM simply guides a probe along thesurface of the part or object to be measured. The measurement data arethen recorded and provided to the user. In some cases, the data areprovided to the user in visual form, for example, three-dimensional(3-D) form on a computer screen. In other cases, the data are providedto the user in numeric form, for example when measuring the diameter ofa hole, the text “Diameter=1.0034” is displayed on a computer screen.

An example of a prior art portable articulated arm CMM is disclosed incommonly assigned U.S. Pat. No. 5,402,582 ('582), which is incorporatedherein by reference in its entirety. The '582 patent discloses a 3-Dmeasuring system comprised of a manually-operated articulated arm CMMhaving a support base on one end and a measurement probe at the otherend. Commonly assigned U.S. Pat. No. 5,611,147 ('147), which isincorporated herein by reference in its entirety, discloses a similararticulated arm CMM. In the '147 patent, the articulated arm CMMincludes a number of features including an additional rotational axis atthe probe end, thereby providing for an arm with either a two-two-two ora two-two-three axis configuration (the latter case being a seven axisarm).

Three-dimensional surfaces may be measured using non-contact techniquesas well. One type of non-contact device, sometimes referred to as alaser line probe, emits a laser light either on a spot, or along a line.An imaging device, such as a charge-coupled device (CCD) for example, ispositioned adjacent the laser to capture an image of the reflected lightfrom the surface. The surface of the object being measured causes adiffuse reflection. The image on the sensor will change as the distancebetween the sensor and the surface changes. By knowing the relationshipbetween the imaging sensor and the laser and the position of the laserimage on the sensor, triangulation methods may be used to measure pointson the surface.

While existing CMM's are suitable for their intended purposes, what isneeded is a portable AACMM that has certain features of embodiments ofthe present invention.

SUMMARY

In accordance with one embodiment of the invention, a system formeasuring three-dimensional coordinates of an object in space isprovided. The system includes an portable articulated arm coordinatemeasuring machine (AACMM) in a AACMM frame of reference having anorigin, the AACMM having a manually positionable arm portion, a base, anoncontact measurement device, and an electronic circuit, the armportion having an opposed first end and second end, the arm portionincluding a plurality of connected arm segments, each of the pluralityof connected arm segments including at least one position transducer forproducing a plurality of position signals, the first end connected tothe base. A first electronic circuit is configured for receiving theposition signal from the at least one position transducer and forproviding data corresponding to a position of the measurement device,the first electronic circuit having a first processor. A secondelectronic circuit is disposed within the second end, the secondelectronic circuit having a second processor, a first communicationsswitch and a second communications switch. A first data bus is coupledbetween the first electronic circuit and the second electronic circuit,the first data bus configured to operate on a first communicationsprotocol. A second data bus is coupled between the first electroniccircuit and the second electronic circuit. A third data bus is coupledbetween the first communications switch and the first electroniccircuit. A fourth data bus is coupled between the second communicationsswitch and the first electronic circuit. A non-contact measurementdevice is coupled to the second end and electrically coupled to thesecond electronic circuit. Wherein the first communications switch andthe second communications switch are configured to operably couple thesecond data bus, the third data bus and the fourth data bus into asingle logical data bus in response to a second signal, the singlelogical data bus configured to operate on a second communicationsprotocol, the second communications protocol being different than thefirst communications protocol.

In accordance with one embodiment of the invention, A method ofoperating a portable articulated arm coordinate measuring machine(AACMM) for measuring three-dimensional coordinates of an object inspace, comprising: providing the AACMM in a AACMM frame of referencehaving an origin, the AACMM having a manually positionable arm portion,a base, a noncontact measurement device, and an electronic circuit, thearm portion having an opposed first end and second end, the arm portionincluding a plurality of connected arm segments, each of the pluralityof connected arm segments including at least one position transducer forproducing a plurality of position signals, the first end connected tothe base; providing a first electronic circuit configured for receivingthe position signal from the at least one transducer and for providingdata corresponding to a position of the measurement device, the firstelectronic circuit having a first processor; providing a secondelectronic circuit disposed within the second end, the second electroniccircuit having a second processor, a first communications switch and asecond communications switch; providing a first data bus coupled betweenthe first electronic circuit and the second electronic circuit, thefirst data bus configured to operate on a first communications protocol;providing a second data bus coupled between the first electronic circuitand the second electronic circuit; providing a third data bus coupledbetween the first communications switch and the first electroniccircuit; providing a fourth data bus coupled between the secondcommunications switch and the first electronic circuit; coupling anaccessory device to the second end; receiving a first identificationsignal at the first communications switch and the second communicationsswitch; switching the first communications switch and the secondcommunications switch to couple the second data bus, the third data busand the fourth data bus into a single logical data bus in response tothe first identification signal, the single logical data bus configuredto operate on a second communications protocol, the secondcommunications protocol being different than the first communicationsprotocol.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, exemplary embodiments are shown whichshould not be construed to be limiting regarding the entire scope of thedisclosure, and wherein the elements are numbered alike in severalFIGURES:

FIG. 1 and FIG. 2 are perspective views of a portable articulated armcoordinate measuring machine (AACMM) having embodiments of variousaspects of the present invention therewithin;

FIG. 3, is a block diagram of electronics data processing systemutilized as part of the AACMM of FIG. 1 in accordance with anembodiment;

FIG. 4 and FIG. 5 are block diagrams of an encoder assembly for thearticulated arm of the AACMM of FIG. 1 in accordance with an embodimentof the invention;

FIG. 6 is a block diagram of the probe end electronics of the AACMM ofFIG. 1;

FIG. 7 is a schematic diagram of a portion of the probe end electronicsof FIG. 6;

FIG. 8 is a schematic diagram of another portion of the probe endelectronics of FIG. 6;

FIG. 9 is a block diagram of the electronic data processing system inaccordance with an embodiment of the invention;

FIG. 10 is a block diagram of a power supply having a redundant energysource for use with the AACMM of FIG. 1 in accordance with an embodimentof the invention;

FIG. 11 is a side illustration of the probe end with the handlepartially disassembled in accordance with an embodiment of theinvention; and

FIG. 12 and FIG. 13 are perspective views illustrating the probe end 103with non-contact measurement devices attached.

DETAILED DESCRIPTION

Portable articulated arm coordinate measuring machines (“AACMM”) areused in a variety of applications to obtain measurements of objects.Embodiments of the present invention provide advantages in allowing anoperator to easily and quickly couple accessory devices that usestructured light to a probe end of the AACMM to provide for thenon-contact measurement of a three-dimensional object. Embodiments ofthe present invention provide further advantages in providing forcommunicating data representing a distance to an object measured by theaccessory. Embodiments of the present invention provide still furtheradvantages in providing power and data communications to a removableaccessory without having external connections or wiring. Embodiments ofthe present invention further provide for a selectively configurablelogical data bus that may be operated under different communicationsprotocols in response to the accessory coupled to the probe end. Stillfurther embodiments of the invention provide for a power supply havingredundant energy sources that allows for replacement of an energy sourcewithout interrupting operation of the AACMM.

FIGS. 1 and 2 illustrate, in perspective, an AACMM 100 according tovarious embodiments of the present invention, an articulated arm beingone type of coordinate measuring machine. As shown in FIGS. 1 and 2, theexemplary AACMM 100 may comprise a six or seven axis articulatedmeasurement device having a probe end 103 that includes a measurementprobe housing 102 coupled to an arm portion 104 of the AACMM 100 at oneend. The arm portion 104 comprises a first arm segment 106 coupled to asecond arm segment 108 by a first grouping of bearing cartridges 110(e.g., two bearing cartridges). A second grouping of bearing cartridges112 (e.g., two bearing cartridges) couples the second arm segment 108 tothe measurement probe housing 102. A third grouping of bearingcartridges 114 (e.g., three bearing cartridges) couples the first armsegment 106 to a base 116 located at the other end of the arm portion104 of the AACMM 100. Each grouping of bearing cartridges 110, 112, 114provides for multiple axes of articulated movement. Also, the probe end103 may include a measurement probe housing 102 that comprises the shaftof an axis of rotation for the AACMM 100 (e.g., a cartridge containingan encoder system that determines movement of the measurement device,for example a probe 118, in an axis of rotation for the AACMM 100). Inthis embodiment, the probe end 103 may rotate about an axis extendingthrough the center of measurement probe housing 102. In use of the AACMM100, the base 116 is typically affixed to a work surface.

Each bearing cartridge within each bearing cartridge grouping 110, 112,114 typically contains an encoder system (e.g., an optical angularencoder system). The encoder system (i.e., transducer) provides anindication of the position of the respective arm segments 106, 108 andcorresponding bearing cartridge groupings 110, 112, 114 that alltogether provide an indication of the position of the probe 118 withrespect to the base 116 (and, thus, the position of the object beingmeasured by the AACMM 100 in a certain frame of reference—for example alocal or global frame of reference). The arm segments 106, 108 may bemade from a suitably rigid material such as but not limited to a carboncomposite material for example. A portable AACMM 100 with six or sevenaxes of articulated movement (i.e., degrees of freedom) providesadvantages in allowing the operator to position the probe 118 in adesired location within a 360° area about the base 116 while providingan arm portion 104 that may be easily handled by the operator. However,it should be appreciated that the illustration of an arm portion 104having two arm segments 106, 108 is for exemplary purposes, and theclaimed invention should not be so limited. An AACMM 100 may have anynumber of arm segments coupled together by bearing cartridges (and,thus, more or less than six or seven axes of articulated movement ordegrees of freedom).

The probe 118 is detachably mounted to the measurement probe housing102, which is connected to bearing cartridge grouping 112. A handle 126is removable with respect to the measurement probe housing 102 by wayof, for example, a quick-connect interface (FIG. 10). As will bediscussed in more detail below, the handle 126 may be replaced withanother device configured to provide non-contact distance measurement ofan object, thereby providing advantages in allowing the operator to makeboth contact and non-contact measurements with the same AACMM 100. Inone embodiment, the non-contacting measurement device may be a laserline probe or structure light image scanner 400 (FIGS. 12-13). Inexemplary embodiments, the probe 118 is a contacting measurement deviceand is removable. The probe 118 may have different tips that physicallycontact the object to be measured, including, but not limited to: ball,touch-sensitive, curved and extension type probes. In other embodiments,the measurement is performed, for example, by a non-contactingmeasurement device such as an interferometer or an absolute distancemeasurement (ADM) device. In an embodiment, the handle 126 is replacedwith the laser line probe or the coded structured light scanner deviceusing the quick-connect interface. Other types of measurement devicesmay replace the removable handle 126 to provide additionalfunctionality. Examples of such measurement devices include, but are notlimited to, one or more illumination lights, a temperature sensor, athermal scanner, a bar code scanner, a projector, a paint sprayer, acamera, or the like, for example. In some embodiments, a combination ofthe foregoing measurement devices may be coupled to the AACMM 100simultaneously.

As shown in FIGS. 1 and 2, the AACMM 100 includes the removable handle126 that provides advantages in allowing accessories or functionality tobe changed without removing the measurement probe housing 102 from thebearing cartridge grouping 112. As discussed in more detail below withrespect to FIG. 6, the removable handle 126 may also include anelectrical interface that allows electrical power and data to beexchanged with the handle 126 and the corresponding electronics locatedin the probe end 103.

In various embodiments, each grouping of bearing cartridges 110, 112,114 allow the arm portion 104 of the AACMM 100 to move about multipleaxes of rotation. As mentioned, each bearing cartridge grouping 110,112, 114 includes corresponding encoder systems, such as optical angularencoders for example, that are each arranged coaxially with thecorresponding axis of rotation of, e.g., the arm segments 106, 108. Theoptical encoder system detects rotational (swivel) or transverse (hinge)movement of, e.g., each one of the arm segments 106, 108 about thecorresponding axis and transmits a signal to an electronic dataprocessing system within the AACMM 100 as described in more detailherein below. Each individual raw encoder count is sent separately tothe electronic data processing system as a signal where it is furtherprocessed into measurement data. No position calculator separate fromthe AACMM 100 itself (e.g., a serial box) is required, as disclosed incommonly assigned U.S. Pat. No. 5,402,582 ('582).

The base 116 may include an attachment device or mounting device 120.The mounting device 120 allows the AACMM 100 to be removably mounted toa desired location, such as an inspection table, a machining center, awall or the floor for example. In one embodiment, the base 116 includesa handle portion 122 that provides a convenient location for theoperator to hold the base 116 as the AACMM 100 is being moved. In oneembodiment, the base 116 further includes a movable cover portion 124that folds down to reveal a user interface, such as a display screen.

In accordance with an embodiment, the base 116 of the portable AACMM 100contains or houses an electronic circuit having an electronic dataprocessing system that includes: a base processing system that processesthe data from the various encoder systems within the AACMM 100 as wellas data representing other arm parameters to support three-dimensional(3-D) positional calculations; and a user interface processing system,an optional display, and resident application software that allows foroperation of the AACMM 100. In one embodiment, the application softwareallows for relatively complete metrology functions to be implementedwithin the AACMM 100 without the need for connection to an externalcomputer.

The electronic data processing system in the base 116 may communicatewith the encoder systems, sensors, and other peripheral hardware locatedaway from the base 116 (e.g., a noncontact distance measurement devicethat can be mounted to the removable handle 126 on the AACMM 100). Theelectronics that support these peripheral hardware devices or featuresmay be located in each of the bearing cartridge groupings 110, 112, 114located within the portable AACMM 100.

FIG. 3 is a block diagram of electronics inside base 116 utilized in anAACMM 100 in accordance with an embodiment. The embodiment shown in FIG.3 includes an electronic data processing system 210 including a baseprocessor 204 for implementing the base processing system, a userinterface board 202, and a base power board 206 for providing power. Theelectronic data processing system 210 may further include wirelesscommunications circuits, such as a Bluetooth module or a Wifi module(not shown). The user interface board 202 may include a computerprocessor for executing application software to perform user interface,display, and other functions described herein.

In the exemplary embodiment, the electronic data processing system 210includes a first Ethernet communications module 220 that allows the baseprocessor 204 to communicate with external devices, such as via a localarea network for example. The electronic data processing system 210further includes a second Ethernet communications module 222. TheEthernet module 222 is coupled for communication with an interface 224that connects the Ethernet module 222 to an arm bus 242 that forms adirect communications circuit between a device (e.g. probe 118 or anoncontact measurement device) located on the end of the arm 104 and theelectronic data processing system 210. As will be discussed in moredetail herein, the connection 226 allows for communication via GigabitEthernet communications protocol. The interface 224 further connects thearm bus 218 with a trigger and capture module 236 that accepts signalsfrom the probe end 103 related to the actuation of buttons and thecapturing of coordinate data. The interface 224 further connects the armbus 218 with an RS-485 transceiver 238. As will be discussed in moredetail herein, the transceiver 238 receives signals from a first busthat is coupled to each of the encoders within the articulated arm. Inone embodiment, the signals received by the transceiver 238 aretransmitted by a module 245 to the base processor 204 via a universalserial bus (USB) connection.

The electronic data processing system 210 is in communication with theaforementioned plurality of encoder systems via a portion of the bus218. As will be discussed in more detail below, in the exemplaryembodiment, each of the encoder systems is coupled to a first bus 242that communicates data using the RS-485 protocol. In the embodimentdepicted in FIG. 4 and FIG. 5, each encoder system generates encoderdata and includes: an encoder arm bus interface 214, an encoder digitalsignal processor (DSP) 216, an encoder read head interface 234, and atemperature sensor 212. Other devices, such as strain sensors, may beattached to the encoder arm bus interface 214.

Now referring to FIG. 6, the probe end electronics 230 are incommunication with the arm bus 218. The probe end electronics 230include a probe end processor 228, a temperature sensor 212, ahandle/button interface 240 that connects with the handle 126 or thenoncontact distance measurement device 400 via the quick-connectinterface in an embodiment, and a probe connection 226. Thequick-connect interface 247 (FIG. 11) allows access by the handle 126 tothe data bus, control lines, and power bus used by the noncontactdistance measurement device 400 and other accessories. In an embodiment,the probe end electronics 230 are located in the measurement probehousing 102 on the AACMM 100. In an embodiment, the handle 126 may beremoved from the quick-connect interface 247 (FIG. 11) and measurementmay be performed by the noncontact distance measurement device 400communicating with the probe end electronics 230 of the AACMM 100 viathe arm bus 218. The quick-connect interface 247 may be the same as thatdescribed in commonly owned United States Patent Publication2013/0125408, the contents of which are incorporated herein byreference. In an embodiment, the electronic data processing system 210is located in the base 116 of the AACMM 100, the probe end electronics230 are located in the measurement probe housing 102 of the AACMM 100,and the encoder systems are located in the bearing cartridge groupings110, 112, 114. The probe connection 226 may connect with the probe endprocessor 228 by any suitable communications protocol, includingcommercially-available products from Maxim Integrated Products, Inc.that embody the 1-Wire® communications protocol.

As discussed above, the arm bus 218 is comprised of a plurality ofbusses that may be selectively configured to cooperate and operate underdifferent communications protocols. In the exemplary embodiment, the armbus 218 is a logical data bus comprised of a first bus 242, a second bus244, a third bus 246. The first bus 242 is a two wire bus that isconfigured to operate using the RS-485 communications protocol. Thefirst logical data bus or “A” bus 242 is coupled between the processor228 and the electronic data processing system 210 and each encoder armbus interface 214. In this way, the first bus 242 transmits encoder datathat allows the electronic data processing system to determine theposition and orientation of the probe end 103 and thus the coordinatesof a measured point or points. The second logical data bus or “B” bus244 is also a two-wire bus. Referring to FIG. 7 with continuingreference to FIG. 6, the third logical data bus or “C” bus 246 isselectively coupled using X and Y signals 249 by a switch 250 to allowdirect transmission of data from the combined Bus B 244 and Bus C 246 tothe processor 228. The X and Y signals 249 may be generated by theprocessor in response to receiving LLPID0 and LLPID1 signals 251 fromthe attached accessory device, such as the laser line probe. The LLPIP0and LLPIP1 signals 251 are transmitted by the accessory device tofacilitate identification of the accessory device by the processor 228.In the exemplary embodiment, the accessory identification data may besubsequently relayed to the base processor 204 via bus 242. When theLLPID0 and LLPID1 signals 251 identify an accessory device whichsupports 10/100 Ethernet, the switch 252 defines a connection from theaccessory device (i.e. LLP) to allow signals from the accessory deviceto be transmitted directly to bus 246 without first transmitting throughprocessor 228.

In other embodiments, the X and Y signals 249 may be generated by thebase processor 204 and transmitted to the switch 250. In one embodiment,the signals 249 may be transmitted by the base processor 204 in responseto an input by the operator via an AACMM user interface. In still otherembodiments, the LLPID0 AND LLPID1 signals 251 may be transmitteddirectly from the accessory device (i.e. LLP) to the switch 250. Itshould be appreciated that advantages may be gained by receiving thesignals 251 with the processor 228 in that testing may be performedprior to providing a direct connection between the accessory device andthe bus 246.

It should be appreciated that while the first bus 242 is capable oftransferring data at 6.25 Mb/s, the logical bus formed by thecombination of the second bus 244 up to 100 Mb/s using the 10/100Ethernet communications protocol. Such an increase in capacity may bedesired for some accessory devices, such as the laser line probe 300 forexample, which acquires an increased amount of data when compared with atouch probe.

The fourth or “D” bus 248 is a four-wire bus. Referring now to FIG. 8with continuing reference to FIG. 6, the fourth bus 248 is connected toa second switch 252 that selectively configures the fourth bus 248 tocooperatively operate with the second bus 244 and third bus 246 (whichare selectively coupled via switch 252) to define a logical eight-wirebus that is configured to communicate using the Gigabit Ethernetprotocol. It should be appreciated that the logical eight-wire bus iscapable of transferring data at a rate of up to 1 Gb/s. It isanticipated that in operation the logical eight-wire bus will operate ata data transfer rate of about 500 Mb/s. This increased capacity may bedesirable with certain accessories coupled to the probe end 103, such asnon-contact measurement devices that capture image data at highresolutions, video cameras or multiple accessories coupled to the probeend and operated simultaneously.

In operation, the activation of the switches 250, 252 may be in responseto a signal from the electronic data processing system 210 or the probeend processor 228. In one embodiment, the activation of the switches250, 252 may be in response to an input by an operator, such as throughuser interface board 202 for example, indicating that a particularaccessory device has been coupled to the probe end 103. In anotherembodiment, the probe end processor 228 detects the connection of anaccessory device capable of transmitting large amounts of data andactivates the switches 250, 252 to configure a logical bus that isappropriate for the connected accessory device. It should be appreciatedthat the activation of the switches 250, 252 may be in response to asignal from the probe end processor 228, based on LLPID0 and LLPID1, thebase processor 204 or a combination of the foregoing. One advantage ofswitches 250, 252 is that it allows the selective creation of logicalbuses to provide backwards compatibility with accessories to match thecommunications protocol utilized by that accessory device.

In the exemplary embodiment, the articulated arm 100 includes one ormore slip ring devices that are configured to transmit electrical powerand data across a rotational joint, such at each cartridge grouping 110,112, 114. In one embodiment, the cartridge grouping 110 includes twoslip ring devices, cartridge grouping 112 may include one slip ringdevice (6-axis AACMM) or two slip ring devices (7-axis AACMM), while thecartridge grouping 114 includes three slip ring devices. It should beappreciated that the bus 218 traverses each of these rotational joints.In one embodiment, each slip ring device is configured to transfer 18connections (wires). These connections include six connections for thefirst bus 242, second bus 244 and third bus 246 and four connections forthe fourth bus 248. In addition, there are eight connections forelectrical power, capture and trigger. In the exemplary embodiment, theeighteen connections are divided into two connectors. An exemplary slipring device is model number SRA-73820-1 manufactured by Moog, Inc.

In one embodiment shown in FIG. 9, the base processor board 204 includesthe various functional blocks. For example, a base processor function302 is utilized to support the collection of measurement data from theAACMM 100 and receives raw arm data (e.g., encoder system data) via thearm bus 218 and a bus control module function 308. The memory function304 stores programs and static arm configuration data. The baseprocessor board 204 also includes an external hardware option portfunction 310 for communicating with any external hardware devices oraccessories. A real time clock (RTC) and log 306 and a diagnostic port318 are also included in the functionality in an embodiment of the baseprocessor board 204 depicted in FIG. 9.

The base processor board 204 also manages all the wired and wirelessdata communication with external (host computer) and internal (userinterface board 202) devices. The base processor board 204 has thecapability of communicating with an Ethernet network via an Ethernetfunction 320, with a wireless local area network (WLAN) via a IEEE802.11 LAN function 322, and with Bluetooth module 232 via a parallel toserial communications (PSC) function 314. The base processor board 204also includes a connection to a universal serial bus (USB) device 312.

The base processor board 204 transmits and collects raw measurement data(e.g., encoder system counts, temperature readings) for processing intomeasurement data without the need for any preprocessing, such asdisclosed in the serial box of the aforementioned '582 patent. In anembodiment, the base processor 204 also sends the raw measurement datato an external computer.

The electronic data processing system 210 shown in FIG. 9 also includesa base power board 206 with an environmental recorder 362 for recordingenvironmental data. The base power board 206 also provides power to theelectronic data processing system 210 using an AC/DC converter 358 and abattery charger control 360. The base power board 206 communicates withthe base processor board 204 using inter-integrated circuit (I2C) serialsingle ended bus 354 as well as via a DMA serial peripheral interface(DSPI) 357. The base power board 206 is connected to a tilt sensor andradio frequency identification (RFID) module 208 via an input/output(I/O) expansion function 364 implemented in the base power board 206.

In one embodiment shown in FIG. 10, the base power board 206 includes aninput filter 366 that receives power from an energy source 367 (e.g. awall outlet) and transfers the electrical power to the battery chargercontrol 360. In this embodiment, the battery charger control 360 iselectrically coupled to a first energy storage device and a secondenergy storage device, such as first battery 368 and second battery 370.The battery charger control 360 is configured to transfer electricalpower to (e.g. charge the batteries) and receive electrical power fromthe batteries 368, 370. Each of the batteries 368, 370 includes aprocessing circuit 372 that monitors the voltage, current drain, andbattery temperature via sensors (not shown) in the respective battery368, 370. The battery charger control 360 is further coupled tocommunicate with each processing circuit 372 via a SMBus (I2C) 374 toreceive signals indicating the status of each battery 368, 370.

In one embodiment, the battery charger control 360 is configured tocharge one or both of the batteries in response to a signal from theprocessors 372 when AC electrical power is present. In one embodiment,the battery charger control 360 (the dual battery smart charger 360) maybe configured to charge or withdraw electrical power from one or both ofthe batteries 368, 370 to optimize a parameter, such as battery life oroperation time, based on signals from the processors 372. The batterycharger control 360 may further be configured to selectively withdrawelectrical power from one or both of the batteries 368, 370. In oneembodiment, the battery charger control 360 transmits battery data tothe base processor 204.

In the exemplary embodiment, the batteries 368, 370 are each removablycoupled to the AACMM 100. The batteries 368, 370 and the battery chargercontroller 360 may be configured to allow removal of one or both of thebatteries during operation without interrupting the operation of theAACMM 100. When operating solely on battery power, one of the batteries368, 370 may be removed while the AACMM 100 is operated using electricalpower from the other battery (e.g. hot swappable). It should beappreciated that this dual battery arrangement provides a number ofadvantages in that the batteries provide a redundant power source forthe AACMM 100 in the event that AC electrical power from the energysource 367 is removed or otherwise lost. The dual battery arrangementalso provides advantages in allowing extended, uninterrupted, operationunder battery power since as batteries are drained/depleted, thedepleted battery may be removed and replaced with a new fully chargedbattery. In this way, so long as replacement batteries are available,operation under battery power may extend indefinitely. Further,advantages may be gained in extending the useful life of the batteries368, 370 by operating the battery charger control 360 to lower theaverage current withdrawn from each battery during operation.

Electrical power is transferred from the battery charger control 360 toa conditioning module 376 that also interfaces with a power actuator378. The power actuator 378 allows the operator to selectively turn theAACMM 100 on or off. The power conditioning module 376 transfers aportion of the electrical power to the environmental recorder 362. Theremaining electrical power is transferred to a buck-boost module 380 anda buck regulator module 382, which adapt the electrical power to havecharacteristics suitable for use by the electronic data processingsystem 210.

Though shown as separate components, in other embodiments all or asubset of the components may be physically located in differentlocations and/or functions combined in different manners than that shownin FIG. 3. For example, in one embodiment, the base processor board 204and the user interface board 202 are combined into one physical board.

Referring now to FIGS. 12-13, an exemplary embodiment of a probe end 103is illustrated having a measurement probe housing 102 with aquick-connect mechanical and electrical interface that allows removaland interchangeability of accessory devices, such as non-contactmeasurement devices 400. In one embodiment, the device 400 is removablycoupled to the probe end 103 via the coupler mechanism and interface426. In another embodiment, the device 400 is integrally connected tothe probe end 103. In the exemplary embodiment, the non-contactmeasurement device 400 may be a laser line probe or a structured lightscanner having a single camera FIG. 12 or two cameras (FIG. 13). Thedevice 400 may also be an interferometer, an absolute distancemeasurement (ADM) device, a focusing meter or another type ofnon-contact distance measurement device.

The device 400 includes an electromagnetic radiation transmitter, suchas a light source 402 that emits coherent or incoherent light, such as alaser light or white light for example. The light from light source 402is directed out of the device 400 towards an object to be measured. Inone embodiment the device 400 has a single camera 404 (FIG. 12) and inanother embodiment has two cameras 404, 406. Each of the cameras mayinclude an optical assembly and an optical receiver. The opticalassembly may include one or more lenses, beam splitters, dichromaticmirrors, quarter wave plates, polarizing optics and the like. Theoptical receiver is configured receive reflected light and theredirected light from the optical assembly and convert the light intoelectrical signals. The light source 402 and the cameras are bothcoupled to a controller 408. The controller 408 may include one or moremicroprocessors, digital signal processors, memory and signalconditioning circuits.

Further, it should be appreciated that the device 400 is substantiallyfixed relative to the probe tip 118 so that forces on the handle portion410 do not influence the alignment of the device 400 relative to theprobe tip 118. In one embodiment, the device 400 may have an additionalactuator (not shown) that allows the operator to switch betweenacquiring data from the device 400 and the probe tip 118.

The device 400 may further include actuators 412 which may be manuallyactivated by the operator to initiate operation and data capture by thedevice 400. In one embodiment, the optical processing to determine thedistance to the object is performed by the controller 408 and thedistance data is transmitted to the electronic data processing system210 via bus 242. In another embodiment optical data is transmitted tothe electronic data processing system 210 and the distance to the objectis determined by the electronic data processing system 210. It should beappreciated that since the device 400 is coupled to the AACMM 100, theelectronic processing system 210 may determine the position andorientation of the device 400 (via signals from the encoders) which whencombined with the distance measurement allow the determination of the X,Y, Z coordinates of the object relative to the AACMM.

In the exemplary embodiment, the AACMM 100 is configured to transferdata between the device 400 and the electronic data processing system210 via one of the buses 242, 244, 246, 248. The bus used will depend onthe accessory device 400 that is coupled to the probe end 103. Theelectronic data processing system 210 or the processor 228 areconfigured to detect the device 400 and determine the data transfer ratedesired for the connected device 400. Once the device 400 is detected, asignal is transmitted to one or both of the switches 250, 252 to createa logical bus having the data transfer and communications protocolcharacteristics desired for operation of the device 400 with the AACMM100. It should be appreciated that the electrical power for operation ofthe device 400 may be provided by the base power board 206, such as fromthe batteries 368, 370, or from a power supply arranged internal to thedevice 400 (not shown). In still another embodiment, the device 400 maybe powered via an external power cable.

While the invention has been described with reference to exampleembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims. Moreover, the use of the terms first, second, etc. do not denoteany order or importance, but rather the terms first, second, etc. areused to distinguish one element from another. Furthermore, the use ofthe terms a, an, etc. do not denote a limitation of quantity, but ratherdenote the presence of at least one of the referenced item.

What is claimed is:
 1. A system for measuring three-dimensionalcoordinates of an object in space, comprising: an portable articulatedarm coordinate measuring machine (AACMM) having a manually positionablearm portion, having an opposed first end and second end; an electroniccircuit operably coupled to the AACMM; a first data bus coupled betweenthe electronic circuit and the second end, the first data bus configuredto operate on a first communications protocol; a second data bus coupledbetween the electronic circuit and the second end; a third data busoperably coupled between the electronic circuit and the second end; afourth data bus operably coupled between the electronic circuit and thesecond end; and wherein the electronic circuit is operable toselectively couple the second data bus, the third data bus and thefourth data bus into a single logical data bus, the single logical databus configured to operate on a second communications protocol, thesecond communications protocol being different than the firstcommunications protocol.
 2. The system of claim 1 wherein the firstcommunications protocol is RS-485 communications protocol.
 3. The systemof claim 2 wherein the second communications protocol is GigabitEthernet communications protocol.
 4. The system of claim 1 wherein theelectronic circuit is operable to selectively couple the second data busand the third data bus into a second logical data bus, the secondlogical data bus configured to operate on a third communicationsprotocol, the third communications protocol being different than thefirst communications protocol.
 5. The system of claim 4 wherein thethird communications protocol is an Ethernet communications protocol. 6.A method of operating a portable articulated arm coordinate measuringmachine (AACMM) for measuring three-dimensional coordinates of an objectin space, comprising: providing the AACMM in a AACMM frame of referencehaving an origin, the AACMM having a manually positionable arm portionhaving an opposed first end and second end; providing a first data buscoupled between an electronic circuit and the second end, the electroniccircuit being operably coupled to the AACMM, the first data busconfigured to operate on a first communications protocol; providing asecond data bus coupled between the first electronic circuit and thesecond electronic circuit; providing a third data bus coupled betweenthe electronic circuit and the second; providing a fourth data buscoupled between the electronic circuit and the second end; coupling anaccessory device to the second end; and selectively coupling the seconddata bus, the third data bus and the fourth data bus into a singlelogical data bus, the single logical data bus configured to operate on asecond communications protocol, the second communications protocol beingdifferent than the first communications protocol.
 7. The method of claim6 further comprising transmitting first data via the first data bususing the first communications protocol, the first communicationsprotocol being an RS-485 communications protocol.
 8. The method of claim7 further comprising transmitting second data via the single logicaldata bus using the second communications protocol, the secondcommunications protocol being a Gigabit Ethernet communicationsprotocol.
 9. The method of claim 8 further comprising forming a directcommunications circuit from the accessory device to the single logicaldata bus.
 10. The method of claim 9 further comprising transmitting datadirectly from the accessory device to the first processor via the singlelogical data bus.
 11. The method of claim 6 further comprising couplingthe second data bus and the third data bus into a second logical databus, the second logical data bus configured to operate on a thirdcommunications protocol, the third communications protocol beingdifferent than the first communications protocol.
 12. The method ofclaim 11 further comprising transmitting third data via the secondlogical data bus using the third communications protocol, the thirdcommunications protocol being a Ethernet communications protocol.